Dogs understand what we say and how we say it, brain scans show

A Golden Retriever was trained to lie to completely still in a fMRI, which measured its brain activity as the dog listened to its trainer’s speech. Courtesy Enika Kubinyi

By Meghan Holohan, TODAY

(NBC News) - “Good boy! Who’s such a good boy? You’re a good boy!”

These words can cause any dog to wag its tail in excitement. Many believed that dogs responded to the tone, that excited, praising voice, more than the words. But a new study in Science shows that dogs understand tone and words and their brains work to process speech much like humans.

"We talk to dogs all the time but we know little about what they get from all this. If dog brains also process what we say, then we have to re-think what makes words uniquely human," Attila Andics, from Eötvös Loránd University in Budapest and author of the study, told TODAY via email.

The findings provide evidence that comprehending language isn’t only a human ability. And, the researchers also believe the results will provide insight into how dogs develop an understanding of human language.

For the study, Andics and his colleagues had 13 dogs — trained to lie perfectly still in a fMRI — listen to their trainers’ voices while the researchers scanned their brains. Trainers said meaningful words in neutral or praising tone. Then they said meaningless words in a neutral or praising tone.

When dogs heard meaningful words, their left hemispheres lit up with activity, helping them process the words. When dogs heard meaningless words, their right hemispheres flickered with activity as they worked to understand the tone. When words and tone matched both hemispheres activated and worked together to interpret meaning.

"We see now that speech processing mechanisms in dogs and humans are more similar than we thought," Andics said. In humans, the left hemisphere processes language, the right grapples with intonation, and the two partner to make sense of it.

“Praise is rewarding for dogs, but only if both word meaning and intonation match," Andics said.

Do these findings mean it's smart for dog owners to spell out words in front of their dogs when trying to hide something?

That's a trick that might not always work.

Andics believes if a pooch hears the same sequence of letters, such as w-a-l-k, repeatedly in the same context (such as while lacing up your tennis shoes), it will definitely understand that w-a-l-k means exercise. But dogs hear so many words that are meaningless to them, such as conjunctions, that they might simply tune out spelled out words.

While the study is one of the first to look at brain scans to see how non-primates process speech, it isn't the first research isn’t the first to show that dogs share close bond with humans and their evolution alongside us makes for a unique relationship. A 2015 paper found that when dogs and their owners gaze into one another’s eyes humans and dogs experience a surge of oxytocin, aka the cuddle hormone. Humans normally experience increased oxytocin in romantic encounters or after childbirth.

A study last week shows that some dogs crave their owners’ attention so much, they are willing to forgo a treat (a finding that may seem unbelievable to anyone who’s owned a food-obsessed pooch). Even the dogs who prefer the food feel torn by choosing food over their owners.

And another study found that dog will share with other dogs, what’s known as a pro-social behavior, often thought of as a human behavior. Though the paper was unclear whether generosity stems from dogs being pack animals who need to share to survive or their close evolution with humans.

All this goes to show that being human's best friend makes dogs more like us than we realize.